1. Field of the Invention
The present invention relates generally to memory in processor-based or microcontroller-based systems, and more particularly, to an apparatus and method of emulating random access memory using a processor register set.
2. Description of the Related Art
In processor-based systems, read only memories (ROM) are configured to store information that has been written during the manufacturing process, but which cannot be written to during the normal operating process of the system. Random access memories (RAM) store information that can be directly and randomly read or written. The information stored in ROM is non-volatile (i.e., the information is retained when power is turned off), while that stored in RAM is volatile (i.e., information is lost when power is turned off). Boot routines and the PC BIOS routines are typically stored in ROM because information is retained when power is turned off.
However, information cannot be written to ROM and data that is stored in ROM typically cannot be altered, and when alteration is possible, it is difficult. As a result, an application program such as application software and/or firmware that is executed during power up or before RAM has been initialized and made accessible, has limited applications. This is because it cannot store information in ROM. For example, such application software cannot write e.g., store variables, build lists, or implement deeply nested procedures which utilize high level languages.
Accordingly, there is a need in the technology for an apparatus and method for overcoming the aforementioned problems. In particular, there is a need for an apparatus and method for enabling applications to write to a storage location prior to availability and accessibility of RAM in a processor system.